Projection device for television apparatus



March 16;,x "1943'. McD, BUNDLE 2,438,022

PROJECTION DEVICE FOR TELEVISION APPARATUS Filed March 22, 1945 INVENTOR. fi-a if 3 mmyww fiu/vazi r r '7 By Patented Mar. 16, 1948 PROJECTION DEVICE FORTELEVISION APPARATUS Henry McD. Bundle, Moorestovm, N. 1., asslznor to Radio Corporation of America, a corporation of Delaware Application March 22, 1945, Serial No. 584,095

8 Claims.

1 This invention relates to television devices and is directed, in particular, to improvements in television cabinets and optical image projection systems whereby television images and the like may be conveniently viewed in enlarged form.

It has frequently been customar in television apparatus to provide a television image producing tube and optical system which directs the optical image upwardly through the cabinet and, then, with such a system, a reflecting surface supported on the inner surface of the cabinet lid is used to provide a light directing and imaging element when the cabinet lid is opened to a suit able viewing angle.

Provisions have also been made in the prior art, with arrangements or" the general type shown, for instance, by U. S. Patent No. 2,273,801, granted on February 17, 1942, to D. O. Landis, whereby a mirror or reflecting surface is arranged to direct and focus the light rays forming the enlarged television image upon a planar vertically positioned viewing screen area.

In arrangements of the lastnarned type, as utilized in the prior art, it will be appreciated that by permanently positioning the reflecting surface at an angle of approximately 45 to the axis of the optical system so as to direct the light image from the cathode ray image pro= ducing tube and its associated optical system toward a viewing screen, which was positioned at 45 to the reflector and in the focal plane of the optical system, the cabinet structure became unduly high because of the permanent location and fixed position of both the reflecting element and the viewing screen.

Other arrangements of the prior art, such as the Zworykin U. S. Patent No. 1,870,702, granted August 9, 1932, have provided the reflecting element within the lid of the television cabinet, as aforesaid, but have not made provisions for the utilization of an auxiliary image viewing screen element upon which substantial enlargements of the television image produced upon the target area of the cathode ray tube are obtained.

Accordingly, it becomes an object or" the present invention to provide a more convenient arrangement for viewing enlargements of television images while maintainin the size of the cabinet structure within reasonable and moderate limits, so that an attractive cabinet appearance is retained while still all of the beneficial effects of eiiicient image projection and enlarging apparatus are attained.

Other objects of the invention are those of providing a. cabinet structure for enabling viewers to see enlargements of television or other types of produced images on a suitable translucent or other appropriate form viewing screen area when the apparatus cabinet lid structure is in an opened position, and to provide a cabinet structure, which, when the lid is in a closed position, will be a compact instrumentality in which the image viewing screen will disappear from sight so as to protect it from breakage, as well as reduce the cabinet size.

Other objects of the invention are those of providing an efficient mechanical arrangement for eilecting the location of an image viewing screen in proper focal position upon the opening of the cabinet lid, and for providing a convenient way by which the viewing screen may readily be housed within the cabinet with a closure of the lid.

Other objects-0f the invention are those of providing convenient methods and means by which the inner areas of the cabinet structure itself may be made inaccessible from without to protect lockers against touching high voltage connections and the like or having access to the instrumentalities within the cabinet when the lid structure is opened. At the same time, it is an object of the invention to provide a masking means whereby the optical images passed through the optical system within the cabinet structure to the reflecting element and, thence, to the viewing screen shall be masked against the influence of any external light which might tend to form objectionable background lighting on the light impinging side of the viewed screen.

are read in connection with the accompanying drawings, wherein Fig. 1 is a front elevation of th television cab inet with the image viewing screen in viewing position;

Fig. 2 is a side elevation of the cabinet structure of Fig. 1 with a portion broken away to show the operation oithe viewing screen posi. tioning mechanism;

F18. 3 is a sectional view taken on the line 8-3 of Fig. 1; and,

Fig. 4 is a partial sectional view of the general cabinet arrangement of Fig. 3, with the cover portion of the cabinet substantially closed.

In its preferred form, the invention comprises essentially a cabinet base structure of substan-- tially rectangular parallelopiped form, in one section of which there is located a television image producing tube and its associated optical system, and in the upper area of which there is provided a hinged cover element serving to close the structure in its closed position, and serving in its open position to reflect the light of the image producing tube and its associated optical system toward a viewing screen element. The viewing screen is pivotaily supported in a support frame which has one edge hinged to the cabinet lid. At its other edge portion the viewing screen support frame is suitably positioned in such a manner relative to the cabinet as a whole that, upon full opening of the cabinet lid, the viewing surface is located exactly at the focal point of the optical image projection system.

Referring now more particularly to the drawin s for a further understanding of the invention, the cabinet base structure ii is arranged to house suitable electronic apparatus (not shown) for converting electrical or radio signals into video or image signals which serve to control or modulate an image producing cathode ray tube. The housed apparatus is used, also, for converting accompanying, or even separate and unrelated, audio signal modulations into sound signals which are to be effective to actuate a suitable sound reproducing element. vWhile this electronic apparatus has not been shown, for reason of convenience of illustration, it may be and support in substantially any desired position.

assumed, essentially, that it is contained within I the main cabinet structure andv a part of it, at least, supported on the ledge structure it. Suitdeveloped within the tube is so that the controlled intensity cathode raybeam, when impacting the fluorescent screen or target area 2! and when swept thereacrossin a bidimensional path to form the well known image raster, causes the electro-optical television image to beproduced. The optical image projection and enlarging system herein shown is equally adapted for black and white monochrome image representations and for image representations in natural color, but for convenience of illustration, the arrangement has been illustrated as applicable merely to monochrome.

The upper section of the cabinet has a lid or cover structure 23 hinged thereto along its edge 25 so that the lid may be opened and closed relative to the main cabinet .body, as indicated by the arrows. A reflecting element 21 is positioned on the inner surface of the lid 23. The reflecting element or mirror 21 serves to reflect any light images directed thereupon from within the cabinet toward a viewing screen surface 29 used for image observation by an audience. The viewing screen 29 is of any suitable and desired.character. It is usually formed of translucent glass or plastic, or it may be formed in any other man-,

ner provided it serves to exhibit optical images to a viewing audience. The viewing screen (which is not per se a part of this invention) is preferably carried in a support element or frame 3! which is attached or suitably hinged by means of a hinge 33 to the edge 35 of the cabinet lid 23.

The cabinet lid is so arranged that a compression spring element 37 acting through the link mechanism 39 serves as a counterbalancing mechanism to provide easier lid opening and closing and, at the same time, provides lid balance If it be assumed, for instance, that the cabinet lid 23 is in the position shown by Fig. 3, it will i be firmly supported so that the angle made with able external tuning, volume, and other operational controls are provided by the conventionally represented knob or knobs ii. the support ledge 55 may be used to. mount, at least, the head end of the receiver instrumentality. For convenience of operation and as an aid in tuning and adjusting, this portion of the receiver structure may be pivoted on a hinge unit it so as to swing outwardly from the cabinet body itself. In this way, if the various components,

such as receiver tubes, supported upon the ledge it are in a vertical position with the arrangement in the position shown by Fig. 3, a pivoting of the section about the hinge it? will bring the tubes or other elements externally of the cabinet to a position varying, for instance, between to the vertical and a horizontal position depending upon the location of a suitable stop member (not shown) which will serveto limit the motion. The power supply system likewise is not shown, but is preferably mounted in the lower portion of the cabinet structure.

When signal energy, as received, is converted into demodulated video or image control signal impulses, these signals are applied to control or modulate a cathode ray image producing tube, conventionally represented at is, to produce, in known manner, on the fluorescent or luminescent viewing "screen or target area 2i thereof a suitable electro-optical television image. The method and operation of a tube of this character is so well known that it-will require no further description other than to state that the received signals serve to modulate a cathode ray beam Where desired,

a vertical line through the cabinet body or base member is of the general order of 45 relative to the optical axis of a contained image projection system. In this arrangement, the viewing screen 29, carried in its frame support 3! and hinged at 33 to the free end 35 of the'cabinet lid, will be swung outwardly and rotate about the hingett as a center until it assumes substantiallythe vertical position shown in any of Figs. 1, 2 or 3. In this position the screen 29 is at 45 to the mirror element 2?.

A guide track or cam slot ii is provided in the plate element 33 supported from the sides or the main cabinet body member ii to control the screen motion'with an opening or closing of the cabinet lid. A suitable cam follower or roller 65 is located in the cam slot ti so that, as the lid opens, the roller or follower d5, which is attached to the lid, moves in the slot or track ii in the direction indicated by the arrow adjacent the plate 63 in Fig. 3 and finally comes to rest at the extreme right edge thereof. In this extrem position, the viewing screen 29 and its frame are supported both from the hin-geelement 33 on the cabinet lid 23 and by the cam roller or follower 65 bearing upon the cam track 4|. Also, at this assumed position, the viewing screen element comes to a vertical position and makes an angle of 45 with a cabinet lid and associated mirror 27 in its opened position. At the same time, the location of the viewing screen 29 relative to the optical system, later to be described, is such that the plane of the viewing screen is exactly at the focal plane of the said optical system so that cacao sharpl defined images are always produced on the viewing screen.

Masking elements or side curtains 41 are also carried and supported pivotally by one end of the hinge member 35. These masking elements are located externally to any light path from the optical system, later to be described, and the viewing screen 29 and approximately in the plane of the uprightframe supports 3| providing the support in located arrangement for the viewing screen 29. The masking elements 41, of which there may be a plurality, are essentially sector.

shaped plates which are adapted to close inside one another. They are attached to each other by means of pins 49 and 50 moving within slots and 52, for instance, so that as the lid structure is opened, the first side masking element 41 which has one edge attached to the frame support 3! by means of a clamp 53, for instance, draws the adjacent sector shaped element away from the cabinet lid and it then pulls thenext section by means of the pin 49 sliding in the slot II which is, in turn, followed by the guiding of that sector shaped element in the slot52 by means of the pin 59. The last sector plate has one edge attached to the cabinet lid, as indicated. The sector shaped elements, as shown by Figs. 2 and 3, serve to mask oil the outer edge of the cabinet and provide the eiiect of both a shadow box for viewing images upon the screen 29, as well as to provide a means whereby access to the cabinet from the edges between the lid 23 and the screen 29 or its frame 3| becomes impossible. This serves as one means to protect the viewer and user, as above noted, against any eiiects of high voltages on operating parts or the like within the cabinet structure.

With the cabinet lid 23 in the position indicated by any of Figs. 1, 2-or 3, images appearing on the viewing screen 29 may be viewed by observers generally in front of the screen 29 so that they view it substantially in the manner that the screen is viewed in looking at Fig. 1 of the drawings. In this form of arrangement, the image producing tube l9, which, as above noted, has produced a television image on the luminescent target area 2 I, projects that television image along an optical path conventionally represented at 55 toward a spherical reflecting element 5'! which is suitably held and supported in the lower section of the cabinet by means of a support frame 59 or the like. The image which has been projected upon the reflecting surface 57 is then reflected therefrom along the optical paths conventionally represented at 5! and 63 toward the mirror surface 21 carried in the cabinet lid. The impinging light rays then are, in turn, reflected along the indicated optical paths 65 and 67, respectively, to focus. for instance, in the plane of the viewing screen, such as at the point 69. At an intermediate point in the optical path, an aspheric zone plate II (also termed a correcting plate) is positioned to receive the light reflected from the reflecting surface 51. The aspheric zone plate H arranged external to the light path from the image producing tube to the reflector and axially in line with each. It is arranged to correct for any spherical aberrations introduced into'the reflected light rays by the curved reflecting surface 51 so that a sharply focused enlargement of the image developed upon the fluorescent or luminescent target area 2| of the tube I9 is produced on the viewing screen 29.

An arrangement for positioning and locating the aspheric zone plate relative to the, cathode 6 ray image producing tube, such as i9, and its associated spherical reflector Bl, is shown and described by the above-mentioned U. S. patent granted to D. 0. Landis (Patent No. 2,273,801), and, therefore, will not be described herein in any considerable detail in that reference may be made to the aforesaid patent for details as to the construction and arrangement of the plate and the broad features of its use as a part of the optical system. For the purpose of these considerations, the aspheric zone plate I i may be assumed to have a central opening for the purpose of passing the tube neck, the mounting of which is not shown in detail. The zone plate maybe supported on its edges or periphery by causing it to overlap properly a suitable opening in a support surface l3 which, in turn, is carried by the cabinet proper. The aspheric zone plate ll may then be positioned and adjusted laterally in various positions relative to the optical axis by means of the adiusting screws'15, for instance, to provide the desired corrections and to establish a correct image focus at the viewing screen. The adjusting screws are preferably carried in the bracket elements 'Il supported on the support element or plate 13.

Thus, signals received by the complete receiver instrumentality and used to control or modulate the cathode ray beam developed within the tube l9 eventually initiate the production of enlarged television images upon the screen 29. Signals representative of the sound eifects may independently control the modulation of a suitable loud speaker unit, conventionally represented at '19, positionedinternally of the grill BI and protected from the outside by means of the grill members 83.

At times when images are not to be viewed, the cabinet lid may be closed according to the showing of Fig. 4, In this position, it will be seen .that the viewing screen 29, and its support frame 3!, is carried to a position substantially parallel to the lid structure 23 by means of the hinges or supports 33 provided and by means of the cam roller or follower 45 being guided in the cam track toward the extreme position conventionally represented at 85. At the same time, the sector shaped masking plates 41 telescope within one another to provide a compact mask which fits within the upper areas of the complete cabinet structure. When the lidis completely closed, the edge 81 of the top section forms the upper part of the cabinet front 89 and comes to rest immediately inside the edge of the front panel 89.

In the event that it is desired to separate cornpletely the viewing area of the cabinet from that portion of the cabinet wherein high voltages appear and wherein the image and sound effects are produced, a suitable sheet of safety glass, represented at 9!, may be mounted completely transverse to the cabinet structure. The safety glass 9! then serves to protect any viewers from the possible effects of both the high voltages present on the electrical apparatus contained within the cabinet and also from the effects of any implosions of the cathode ray tube or the like due to tube breakage, electrical failures or the like which might tend to be harmful externally of the cabinet, as well as within the cabinet. In this connection, it should be noted that the safety glass surface 81 should preferably be treated so as to be completely non-reflecting and substantially completely transparent in order that image distortions and the like resulting from the passage of the-light rays through the cabinet, as a 7 v whole. and through the protecting glass sheet, in

particular, shall not be experienced.

A still further feature of the safety glass sheet 9|, which is shown as extending transversely of the cabinet body, is that it serves as a means by which dust and dirt are kept fromwithout the cabinet body; It is important in connection with apparatus utilizing high voltages that precautions or a very light touch upon the free end of the screen support which rests against the front panel 89.

Other modifications, of course. will become obvious to those skilled in the art to which the invention is directed.

be taken to prevent dust or other foreign substances from coming within reach of high voltage portions, because in the event that any static charge is built upon any parts of the apparatus, the dirt or other collected matter will readily attach itself thereto andimpair the efficient operation of the'c'omplete optical system;

- Having now described the invention in one of its preferred forms, it will be appreciated that the arrangement is equally applicable to use in connection with cabinets of the type wherein theimages are developed from different typs of image producing units, as well as where the images are' developed from motion picture film projection apparatus located within the cabinet,'as a whole, and arranged to project the optical images along a suitable path toward the reflecting surface such that the final image shall be observed on 'the viewing screen 29. Also, it is to be-understocd that the invention is equally applicable to systems ofthe type wherein the image is produced upon the cathode ray tube and projected directly through a suitable enlarging lens system toward the reflecting surface of the'lid, in which case the spherical reflector and the aspheric zone plate may be dispensed with and a suitable enlarging lens system of the general type shown by the in a closure member functioning to close any por-' tion of the cabinet base member may be located in other positions than as a top closure element. An example of sucha construction would be in connection with a movable panel which might be considered to hinge to the cabinet base in such a way as to turn about a vertical axis and form a closure element for the sides or ends of the cabinet. In this arrangement, the image producing tube and its optical system would generally be mounted so the optical axis is horizontal within thecabinet and the images projected on the viewing screen would then be viewed at the side of the cabinet; Also, as a further modification, the cabinet may be provided with a hinged front panel section comprising either the entire front panel or a part thereof, and the general arrangement may then be in accordance with the above disclosed modifications changing insofar as is necessary in accordance with the positioning of the movable closure member. For reasons of convenience of illustration no final viewingscreen positioning or locking means has been shown; It will be understo'oihowever, that various forms of devices for this purpose may be used One suitable form of locking unit of the resilient type would be in thefiorm of a spring pressed ball detent which would serve to, maintain the critical position of the viewing screen in the focal planeof the optical system and correcting plate it, but which might readily be disengaged with a very slight closing force exerted upon the cabinet lid Having now described the invention, what is claimed and desired to be secured by Letters Patent is the following: a

1. A viewing structure for image projection apparatus comprising a cabinet base member, a closure element hinged to said cabinet base member, and a planar viewing screen and support,

frame unit having one lateral edge hinged to said cabinet closure element, a cam slot positioned on said cabinet base member for guiding the opposite free edge of the viewing screen and support frame unit and a slidable connection between the free edge of the said screenand support frame and the guide track for positioning the said viewing screen so that its planar surface is in substantial- 1y a vertical viewing position when the cabinet closure member is opened to the operating position relative to a predetermined path along which optical images are adapted to be projected from within the cabinet base memberand also for 10- eating the said viewing screen in a plane substantially parallel to the closure element when the said closure element is base member. I I 2. A viewing structure for image projection apparatus for use in combination with a cabinet base closed upon the cabinet member comprising a cover element hinged to r the cabinet base member for opening and closing thereon, aviewing screen device having one lateral edge hinged to said cover element, and a cam slot means positioned on said cabinet base member slidably connected to means on the free edge of the viewing screen device for guiding the said viewing screen device to a substantially vertical viewing position when the cover element is opened to substantially a angle relative to the cabinet base member and also for locating the said viewing screen in a' plane substantially parallel to the cover when the said cover element is closed upon the cabinet base member.

3. Image projection and viewing apparatus comprising acabinet base member, a cover element hinged to said cabinet base member for opening and closing relative thereto, an image viewing screen support unit having one lateral edge hinged to the edge of the cover element opposite the said cabinet base hinge, a viewing screen element carried by the support unit, a guide means for guiding the opposite edge of the viewing screen support unit with an open position of the cabinet lid to locaterthe screen approximately at a45 angle relative to the cabinet base so that the viewing screen element is in a substantially vertical viewing position and for tumingthe said screen support, unit about its hinge connection with a movement of the cover to a closed position so that the viewing screen is locatcd in a plane substantially parallel and adja-- 'cent to the cover, a reflectorelement supported upon the inner surface of the cover element toreflect optical images developed within the cabinet to the viewing screen element, and light masking means supported by the cover and the screen support unit and pivoted from the end of the cover and screen support unit hinge to mask the light path between the reflector and the viewing screen element from external light.

4. A television image viewing cabinet unit comprising a main base member, a cover element hinged to said'base member for opening and closing relative thereto, an image viewing screen support unit having one lateral edge hinged to the edge of the cover element opp site the hinge connection to said main base member, a slidable guiding means connecting the opposite edge of the viewing screen support means and the main base member so that the cabinet lid when in an open position at approximately a 45 angle relative to the main base member moves the viewing screen support means to substantially a vertical viewing position and so that the said viewing screen support means is moved about its hinge connection with the cover to a, plane substantially parallel and adjacent to the cover when the said cover element is in a closed position upon the base member, a planar viewing screen element carried by said screen support, a reflector element supported upon the inner surface of the cover element to reflect optical images developed within the cabinet to the viewing screen element, and light masking means supported by the cover and the viewing screen support unit and pivoted from the end of the cover and screen support unit hinge to mask the light path between the reflector and the viewing screen element from external light.

5. Image projection and viewing apparatus comprising a cabinet base, a cover element hinged at one edge to said cabinet base so as to be opened and closed relative thereto, a planar viewing screen element, a viewing screen support unit for supporting and positioning the screen element, a hinge connection between one edge of the screen support unit and the edge of the cover element opposite the hinge connection to the cabinet base, a guide element supported upon the cabinet base, a slidable connection between the unhinged edge of the screen support unit and the guide element so that for all positions of the cabinet lid between open and closed the free edge of the screen support unit is controlled in its path of motion and guided to move to a position such that the supported viewing screen element is in a substantially vertical viewing position when the cover element is opened to substantially a 45 angle relative to the cabinet base and is located in a position substantially adjacent the cover element and in a plane substantially parallel thereto when the said cover element is closed upon the cabinet base member.

6. Image projection and viewing apparatus comprising a cabinet base, a cover element hinged at one edge to said cabinet base so as to be opened and closed relative thereto, a viewing screen support frame unit having one lateral edge hinged to an edge of the cover element opposite the hinge to the cabinet base, a planar viewing screen element carried by the viewing screen support frame, a screen support frame guide track element supported upon the cabinet base member, a connection between the unhinged edge of the screen support frame siidably connected to and supported by the guide element whereby, upon opening the cover element to subgtantially a 45 angle relative to the cabinet base, the free edge of the said frame is controlle in its path oi motion by the guide track to swing outwardly for positioning the viewing screen in a substantially vertical plane and whereby, upon closing the cover element onto the cabinet base member, the viewing screen is moved into a posh, tionsubstsntialiy adiacenttoandparslleiwith the said cover element, and a reflector element supported upon the inner surface of the cabinet lid to reflect optical images originating from apbase member, a slidable connection between an unsupported edge of the screen and the guide element for permitting rotary motion of the viewing screen frame support about its hinge connection to the cabinet base when the closure member is opened, and for so limiting the motion of said frame support in an extreme position so as to move the viewing screen to full viewing position, when the closure element is opened to the operating position relative to the main base member, and for locating the said viewing screen, in its other extreme position, in a plane substantially parallel to the closure element when said closure element is closed upon the cabinet main base member.

8. Cabinet apparatus for image projecting and viewing comprising "a main base member, a closure element hinged to the said base member for opening and closing relative thereto, and a viewing screen support frame hingedly connected at one edge to said closure element, a planar viewing screen carried by said support frame element, a guide element, a slidable connection between an unsupported edge of the screen sup port structure and the said guide element for guiding the screen support element so that the screen support element and the viewing screen moves between planes of substantially to each other between positions of complete opening and complete closing of the closure element and such that in a closed position the viewin screen rests in a plane substantially parallel to that of the closure element, image projection apparatus contained within the main base member of the cabinet for directing optical images to focus upon the supported viewing screen element in its opened position, and a transparent member interposed in the base member intermediate the optical system and the hinged closure element to prevent access to the inner portion of the main base member during opening of the closure element and to screen the base member from dust and other foreign matter.

HENRY Mel). BUNDLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

